Earthquake nucleation characteristics revealed by seismicity response to seasonal stress variations induced by gas production at Groningen.

Deterministic earthquake prediction remains elusive, but time-dependent probabilistic seismicity forecasting seems within reach thanks to the development of physics-based models relating seismicity to stress changes. Difficulties include constraining the earthquake nucleation model and fault initial stress state. Here, we analyze induced earthquakes from the Groningen gas
field, where production is strongly seasonal, and seismicity began 3 decades after production started. We use the seismicity response to stress variations to constrain the earthquake nucleation process and calibrate models for time-dependent forecasting of induced earthquakes. Remarkable agreements of modelled and observed seismicity are obtained when we consider (i) the
initial strength excess, (ii) the finite duration of earthquake nucleation, and (iii) the seasonal variations of gas production. We propose a novel metrics to quantify the nucleation model’s ability to capture the damped amplitude and the phase of the seismicity response to short-timescale (seasonal) stress variations which allows further tightening the model’s parameters.